Adsorption of phosphate and mitigation of biofouling using lanthanum-doped quorum quenching beads in MBR Hyeonwoo Choi, Youjung Jang, Jaeyoung Choi, Hyeonsoo Choi, Heekyong Oh and Shinho Chung
Abstract; Full Text (1366K) .	pages 51-57.	DOI: 10.12989/.2024.15.2.051

Abstract
The removal of phosphorus, especially phosphate-form phosphorus, is necessary in wastewater treatment. Biofouling induced by the quorum sensing mechanism is also a major problem in membrane bioreactor (MBR), which reduces membrane flux. This study introduces lanthanum-doped quorum quenching (QQ) beads into MBR, confirming their inhibitory effect on biofouling due to Rhodococcus sp. BH4 and their capacity for phosphorus removal through lanthanum adsorption. A batch test was conducted to access the phosphate adsorption of lanthanum-QQ (La-QQ) beads and lab-scale MBR to verify the effect of inhibition. The study aimed to identify distinctions among the MBR, QQ MBR, and La-QQ MBR. In the batch test, the phosphate removal rate increased as the volume of beads increased, while the unit volume removal rate of phosphate decreased. In the lab-scale MBR, the phosphate removal rates were below 20% in the control MBR and QQ MBR, whereas the La-QQ MBR achieved a phosphate removal rate of 74%. There was not much difference between the ammonia and total organic carbon (TOC) removal rates. Regarding the change in transmembrane pressure(TMP), 3.7 days were taken for the control MBR to reach critical pressure. In contrast, the QQ-MBR took 9.8 days, and the La-QQ MBR took 6.1 days, which confirms the delay in biofouling. It is expected that La-QQ can be used within MBR to design a more stable MBR process that regulates biofouling and enhances phosphate removal.

Key Words
adsorption; biofouling; lanthanum beads; MBR; phosphate removal; quorum quenching

Address
Hyeonwoo Choi, Youjung Jang, Jaeyoung Choi, Hyeonsoo Choi and
Heekyong Oh: Department of Environmental Engineering, University of Seoul, 163 Seoulsiripdaero, Dongdaemun-gu, Seoul 02504, Republic of Korea

Shinho Chung: Department of Environmental Science, Forman Christian College (A Chartered University), Ferozepur Road, Lahore, Punjab, 54600, Pakistan

Enhanced nitrogen removal from high-strength ammonia containing wastewater using a membrane aerated bioreactor (MABR) Arindam Sinharoy, Ji-Hong Min and Chong-Min Chung
Abstract; Full Text (3364K) .	pages 59-66.	DOI: 10.12989/mwt.2024.15.2.059

Abstract
This study evaluated the performance of a membrane aerated biofilm reactor (MABR) for nitrogen removal from a high-strength ammonia nitrogen-containing wastewater. The experimental setup consisted of four compartments that are sequentially anaerobic and aerobic to achieve complete nitrogen removal. The last compartment of the reactor setup contained a membrane bioreactor (MBR) to reduce sludge production in the system and to obtain a better-quality effluent. Continuous experiment over a period of 47 days showed that MABR exhibited excellent NH4+-N removal efficiency (99.5%) compared to the control setup without MABR (56.5%). The final effluent NH4+-N concentration obtained in the MABR was 2.99

Key Words
ammonia nitrogen; biofilm; membrane aerated bioreactor; membrane bioreactor; nitrogen removal; scouring

Address
Arindam Sinharoy, Ji-Hong Min and Chong-Min Chung: Department of Environmental Science & Biotechnology, Jeonju University, Jeonju 55069, Republic of Korea

Application of nickel hexacyanoferrate and manganese dioxide-polyacrylonitrile (NM–PAN) for the removal of Co2+, Sr2+ and Cs+ from radioactive wastewater Md Abdullah Al Masud and Won Sik Shin
Abstract; Full Text (1562K) .	pages 067-78.	DOI: 10.12989/mwt.2024.15.2.067

Abstract
In this study, a nickel hexacyanoferrate and manganese dioxide-polyacrylonitrile (NM–PAN) composite was synthesized and used for the sorptive removal of Co2+, Sr2+, and Cs+ in radioactive laundry wastewater. Single- and multi-solute competitive sorptions onto NM–PAN were investigated. The Freundlich (Fr), Langmuir (Lang), Kargi–Ozmihci (K–O), Koble–Corrigan (K–C), and Langmuir–Freundlich (Lang-Fr) models satisfactorily predicted all the single sorption data. The sorption isotherms were nonlinearly favorable (Freundlich coefficient, NF = 0.385–0.426). Cs+ has the highest maximum sorption capacity (qmL = 0.855 mmol g–1) for NM-PAN compared to Co2+ and Sr2+, wherein the primary mechanism was the physical process (mainly ion-exchange). The competition between the metal ions in the binary and ternary systems reduced the respective sorption capacities. Binary and ternary sorption models, such as the ideal adsorbed solution theory (IAST) model coupled with single sorption models of IAST–Fr, IAST–K–O, IAST–K–C and IAST–Lang–Fr, were fitted to the experimental data; among these, the IAST–Freundlich model showed the most satisfactory prediction for the binary and ternary systems. The presence of cationic surfactants highly affected the sorption on NM-PAN due to the increase in distribution coefficients (Kd) of Co2+ and Cs+.

Key Words
IAST; multi-solute sorption; NM–PAN; radioactive; wastewater

Address
Md Abdullah Al Masud and Won Sik Shin: School of Architecture, Civil, Environmental, and Energy Engineering, Kyungpook National University, 80 Daehakro, Bukgu, Daegu 41566, Republic of Korea

Characterization and performance of post treated PVDF hollow fiber membrane Eman S. Sayed, Hayam F. Shaalan, Magda I. Marzouk and Heba A. Hani
Abstract; Full Text (1570K) .	pages 079-88.	DOI: 10.12989/mwt.2024.15.2.079

Abstract
Modification of Polyvinylidene fluoride (PVDF) hollow fiber membranes (HFMs) characteristics and performance were investigated via post treatment using different oxidants. sodium hypochlorite (NaOCl), hydrogen peroxide (H2O2) and potassium persulfate (KPS). Fourier transform infrared (FTIR) and Proton nuclear magnetic resonance (1H-NMR) results revealed no structural differences after post treatment. Cross-sectional micrographs show finger-like structures at the outer and inner walls of the HFMs and sponge-like structures in middle, where NaOCl and KPS post treated fibers exhibited a decrease in finger-like structures in addition to aggregates appearing on the surface, consequently leading to an increase in the surface roughness (Ra) from 48 nm to 52.8nm and 56 nm, respectively. Hydrogen peroxide post treatment only was observed to decrease the water contact angle from 98° to 81.4°. It was also observed that the elongation at break and the modulus deceased after NaOCl post treatment from 34.5 to 28.5% and from 19.3 Mpa to 16.6 Mpa, respectively. Moreover, pure water flux after H2O2 post treatment increased from 87.8 LMH/bar to 113 LMH/bar at 0.45 bar, while no changes were detected for the methylene blue dye rejection (74%) between raw and hydrogen peroxide post treated fibers at the same pressure. According to the findings hydrogen peroxide post treated PVDF HFMs have the most uniform surfaces, with almost no alterations in structural and mechanical properties or porosities with enhanced hydrophilicity and pure water flux maintaining appropriate rejection. Therefore, it is considered an efficient surface modifying agent for UF/NF membranes or low-pressure separators.

Key Words
characterization; performance; post treatment; PVDF hollow fiber membrane

Address
Eman S. Sayed, Hayam F. Shaalan and Heba A. Hani: Chemical Engineering and Pilot Plant Department, Engineering and Renewable Energy Research Institute, National Research Centre, El-Buhouth Street, Dokki, Giza, Egypt

Magda I. Marzouk: Organic Chemistry Department, Faculty of Science, Ain Shams University, Cairo, Egypt